Automatic pilot



Dec. 16, 1958 A. D. HILL AUTOMATIC PILOT Filed Sept. 21. 1954 2 Sheets Sheet 1 AZQTHU/Q 0. HILL,

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Dec. 16, 1958 A. D. HILL 2,864,990

AUTOMATIC PILOT Filed Sept. 21. 1954 2 Sheets-Sheet 2 srEse/m 5 M0702 Her/ a2 0. xV/LL 11v VENTOR.

Bww/n 5 M United States Patent 6 AUTOMATIC PILOT Arthur D. Hill, Newport Beach, Calif., assignor to Hill- C'unningharn Automatic Pilot Company, Newport lieach, 'Calif., a partnership Application September 21, 1954, Serial No. 457,455

Claims. (Cl. 318-489) This invention relates to automatic pilots, and whereas its application and uses are not limited thereto, it is a principal object of the invention to provide an inexpensive and reliable automatic pilot for small craft such as fishing boats, motor boats, and auxiliary yachts.

The commercial automatic pilots now available for boats of the class described require relatively high voltage and have numerous electronic tubes, generally operating through a photoelectric cell or similar device which sees when the boat is off course. A frequent use of these pilots is during dense fogs, when the human pilot can obtain no bearings or make a land-fall and must set a course by dead-reckoning. At such times failure of the automatic pilot may occur when the pilot is most needed, due to dampness causing the high voltage to are and the tubes to short-circuit. It is accordingly a further object of my invention to provide an automatic pilot which operates on low voltage, thereby minimizing the chances of arcing, and which has no photoelectric cells, electronic tubes, or like apparatus to get out of order.

Another object of my invention is to provide simple and effective means for limitingthe throw of the rudder, these means being individually adjustable as to starboard and port helm. It will be found that when a boat is quartering waves, it will tend to throw oif course much more in one direction than in another, and the advantage of being able to adjust the steering to such conditions in a matter of seconds is appreciable.

Still another object of my invention is to provide an automatic pilot which can be attached either to a tiller or to a wheel-operated rudder, the operating mechanism being capable of reciprocating action to swing a tiller or by a simple conversion to mesh with a gear sector.

In the accompanying drawings illustrative of a presently preferred embodiment of my invention and of certain modifications thereof,

Pig. 1 is a perspective view of the compass of my automatic pilot, the relative orientation of a boat-hull being indicated on a course of 90 magnetic;

Fig. 2 is an enlarged vertical sectional view on the line of section 2-2 of Fig. 1, showing the north-south balancing yoke and the magnetic needle by which it is unbalanced when the boat is off-course;

Fig. 3 is a vertical sectional view on the same scale as Fig. 2, and taken on the line of section 3-3 of Fig. 1, illustrating the cross member of the yoke and the manner in which the magnetic needle unbalances it to make electric contact to starboard or port;

Fig. 4 is a much enlarged vertical sectional view on the line of section 4-4 of Fig. 3, showing the construction of one of the mercury contact cups;

Fig. 5 is a schematic plan view showing the compass connected to a steering motor and the manner in which the steering motor operates the helm of a tiller-steered boat;

Fig. 0 is an enlarged vertical sectional view, taken on "ice the line of section 6-6 of Fig. 5, showing the adjustable compensating mechanism;

Fig. 7 is an enlarged detail of one of the limit switches controlling maximum rudder throw;

Fig. 8 shows a modified form of limit switch, applied directly to the reciprocating apparatus; and

Fig. 9 shows a further modification in which. the device is adapted to a wheel-steered boat, and the compensating mechanism is combined with the limit switches.

Considering now the details of the drawings, I have shown in Fig. 1, in exaggerated proportion to a boat hull it an azimuth card 11 rotatable with respect to the longitudinal axis, or lubber-line, of the boat. Theazimuth card is preferably of reverse azimuth-that is, the degree figures increase in counter-clockwise rotation-and the boat is seen heading on an easterly course of magnetic, the 90 figure being in front of the helmsman.

Mounted on the azimuth card 11, on the 90-270 axis thereof, is a bridge 12 in which is supported a magnetic bar 13, swinging freely in bearings 14. On the (l. axis of the card are two mercury cups 15 and 16 supporting between them the ends of a gimbal bar 17. The central portion of the gimbal bar 17 is depressed below the level of the mercury cups Hand 16 and is provided with a counter-weight 18, which causes the gimbal bar to balance in upright position after the fashion of a mobile.

Attached, as by welding, to the central portion of the gimbal bar 17 is a yoke 29, the two sides of which extend to a considerable elevation above the gimbal bar and,

there loosely stanchion one end of the magnetic bar 13. The ends of the yoke 20 then incline downwardly divergently. A second pair of mercury cups 221 and 22 are placed in an easterly-westerly relationship on the azimuth card 11 and receive the ends 23 and 24 of the yoke 20. The cups 21 and 22 are adjustable in height, having threaded shanks 25 fitted with lock-nuts 26, and are ordinarily adjusted so that neither of the yoke ends 23 or 24 quite makes contact with a drop of mercury 27 contained in the cup, when the yoke 20 is in upright balanced position.

The cup 23 and one of the north-south cups, 15 as illustrated, are co-terminals of a circuit 28 leading to a switching mechanism S, and the cup 22 and the other of the north-south cups 1 6 are co-terminals of a second circuit 29 leading to the same mechanism S which may be a solenoid. The solenoid S is in circuit, through a source of power 39, with a reversible motor 31, shown in Fig. 5. The motor 31 is connected with, and operates the boats rudder 32.

When a course, say of 90, is to be set, the azimuth card is turned to bring the 90 mark to the lubber line, and the boat is turned until the magnetic bar 13 is free within the yoke 2%. With the magnetic bar 13 closely aligned with the earths magnetic field, there is very little power available to tilt the yoke 20.. If the boat swings the magnetic bar 13 will make contact with the yoke 20. Because the yoke 20 extends slightly above the bar 13, an electromagnetic field is generated in the yoke at the instant of contact. This causes the bar 13 to bob up and down, as shown in dotted line in Fig. 3. If the contact is false, caused by the roll of the boat, the bob of the bar 13 will break the contact. But if the contact is real, caused by the boat being off course the bar 13 will come to rest in a position to effectively push the yoke to one side or the other to effectuate steering. Thus the electromagnetic field generated at the instant of contact between the bar 13 and yoke 20 materially assists the bar in tilting the yoke when steering is required.

Preferably the yoke 29 is made of very light wire, such as aluminum, and resists entering the mercury drop 27, making principally a surface contact. This resistanc to the force of the bar 13 in addition to the aforesaid bobbing action, enables me to activate the circuits 28 and 29 with a comparatively light bar closely aligned with the earths magnetic field and therefore having very little intrinsic power. It is, however, important that the wire of the yoke be maintained in light condition and not be permitted to become heavy with mercury amalgam. I have found that burning the ends 23 and 24 of the yoke 20 to carbonize them as shown at 33 in Fig. 4, prevents the formation on them of mercury amalgam. Without such treatment it often happens that one of the ends 23 or 24 will become heavier than the other, and will change the balance of the delicately balanced yoke 20, causing erratic steering. This is particularly true when only one of the cups 21 or 22 is used as a circuit-closer, as hereinafter described, a situation in which the preservation of an accurate balance becomes highly desirable.

The mercury drops 27 have a tendency to evaporate under constantly repeated contacts, but by adjusting the height of the cups 21 and 22 a close contact can be maintained during long cruises with very little tilt of the yoke 20. The cups 15 and 16 of course never break contact with the gimbal bar 17 which is supported by them pivotally.

While the device as described to this point is intended to actuate the solenoid S and the reversible motor 31 and thereby actualy to steer the boat, it is also useful on boats such as sail boats to advise the helmsman when he is off course. The circuits 28 and may be connected to bells of different sounds or to lights of different colors. A yachtsman accustomed to peering into a binnacle at night will appreciate the absence of eye-strain and the relaxation that comes with flashing lights or sounding bells indicating that he should give the boat a right or left rudder.

The normal operation of my automatic pilot includes complete automatic steering, and for this purpose the motor 31 drives a screw shaft 35. A gear follower 36 is suitably guided on the shaft 35 to move forward and back ward thereon as the shaft 35 is reversibly turned. From the follower 36 a link 37 extends to a tiller 38 upon the rudder post 39 of the rudder 32. The link 37 is preferably simply placed upon the posts 4th and 41 on the follower 36 and tiller 38 so that it may be quickly removed. When the link 37 is removed from either the post 46 or the post 41, manual steering may be resumed. Preferably the link 37 has several holes 42 which may fit over either of the posts or 41, to lengthen or to shorten the linkage. Shortening the linkage, as viewed in Fig. 5, would for example result in a slight left rudder as normal, and might be employed to offset the effect of a wind on the port bow.

It is, however, important to compensate for the swing of the craft. Those familiar with the art will understand that a good helsman always swings his rudder back to or beyond a normal position while his vessel is still swinging to the desired compass-point, the weight of the vessel continuing the swing but with constantly diminishing speed. For the purpose of compensation a friction yoke or band 44 is placed around the azimuth card 11. The azimuth card 11 can be turned within the band 44, and is so turned to put the craft upon a new heading, but the band is tight enough on the card so that it will. turn the card unless the card is held. To a suitable fitting 45 upon the band 44 is attached one end of a wire 46 which runs through a surrounding hollow cable 47 and operates in the well-understood manner much like the choke-wire of an automobile, to rotate the band 4 whenever the wire is pushed or pulled. The other end of the wire 46 is fastened by a set screw 48 in a cylindrical fitting 45 which rotates in a block 50 adjustably secured to a swinging post 51. The post 51 is mounted upon the support 52 for the reversible motor 31 and screw shaft 35, so as to pivot at one end on a pin 53 and has a longitudinal slot 54. A bar 55 extends from the gear follower 36, through the proximal end of the slot 53, and as the gear follower 36 is caused to reciprocate, the bar 55 causes the post 51 to swing. The block 50 is adjustable in the slot 54. Thus a given degree of reciprocation of the gear follower 36 will cause a greater or lesser swing of the block 50 and a greater or lesser push or pull upon the wire 46, as desired. However, because of the arcuate movement of the block 50, even the widest swings of the post 51 will result in little terminal movement of the block 50 at the end of the swing, a mechanical action which is the counterpart of the manual compensating action of a good helmsman.

It will be seen from Fig. 5 that if, for example, a movement of the gear follower 36 toward the lower end of the screw shaft 35 gives the craft a right rudder, the same movement will give a pull to the wire 46, beginning slowly, increasing in speed and distance as the swing continues and ending slowly. At the other end of the wire the azimuth card 11 will be rotated correspondingly in a clockwise direction. The craft will have been given a right rudder in the first place because, having swung offcourse to the left, it has caused the magnetic bar 13 to tilt the yoke 20 so that the end 24 makes contact with the mercury in the cup 22. The pull on the wire 26, rotating the azimuth card 11 in a clock-Wise direction, will re-orient the azimuth card into alignment with the bar 13, removing the tilt from the yoke 20 and thus neutralizing it, or will slightly over-compensate and cause the yoke to tilt into the cup 21, reversing the circuit to the solenoid switch S and thus reversing the motor. In short, it will do what a skilled helsman would do.

Even with compensation, it is not desirable to have unlimited swinging, and limit switches 6t) and 61 are provided to break the circuit 62 and 63 fro-m the solenoid switch S to the reversible motor 31. Preferably a rudder card 64 is provided on which the degree of swing of the rudder is indicated by a pointer 65. The pointer 65 is mounted on a post 66 connected to the rudder post 39 by a chain 67 and sprockets 68 and 69. On a slide ring 7h, having the post 66 as its center, are two stops 71 and 72 which may be moved to any point of the ring 76 and fastened there by set-screws 73. The limit-switches 6t) and 61 are normally closed, completing both the circuits 62 and 63 and depending on the solenoid switch S for changing direction of the motor 31. Each has a longer arm 74, swinging in the plane of the respective stop '71 or 72, and a shorter arm '75 which will clear the stop and permit the longer arm 74 to contact the stop.

The stops 71 and 72 can be moved independently and will usually be at different distances from the center point of the rudder card 64, giving a longer swing in one direction than in the other. It will be found that water conditions will require different adjustments of the stops '71 and 72 and of the block 50 governing the amount of steering compensation. Generally when water-conditions permit larger than normal swings between the set limits, the block 50 will be moved down in the slot 54 to give close compensation.

In Fig. 8, I have shown a modification in which limitswitches 77 and 78, instead of being actuated by the rudder post 39, are actuated by movement of the gear-follower 36. The limit-switches are mounted upon a rail '79 running parallel to the traverse of the gear-follower 36, and are movable to different positions thereon, being attached thereto by set-screws 8d. The longer finger 31 of each switch lies in the path of a knob 82 on the gearfollower 36, the shorter finger 83 being arranged to pass the knob.

In Fig. 9, I have shown a further modification or adaptation to boats not provided with a tiller but steered by a wheel. In this modification, the reversible motor 31 drives a pinion gear 85 which acts upon a gear segment 86 attached to the rudder post 39. From the sprocket 69 on the rudder post 39, a chain 87 drives a sprocket 88 on a post 89. The slide ring 70 with stops 71 and 72 are as hitherto described with a similar arrangement of limit switches 60 and 61. However, the rudder indicator pointer 90 now serves as compensator, having attached to it one end of the compensator wire 46. A block 91, in which the compensator wire 46 is secured, is adjustably secured at positions along the swinging pointer 90, thus giving arcuate movement of compensation as described in connection with my preferred embodiment.

Alternatively to having both of the east-west cups 21 and 22 filled with mercury and in circuit with one or another of the north-south cups 15 and 16, only one of them need be a circuit-closing contact, and the other may be a mere stabilizer for the yoke 20. If for example the cup 21 closes a circuit through either of the cups 15 and 16, said circuit including the solenoid switch S, whenever the craft swings off-course to starboard the yoke 20 will be tilted into the cup 21, closing the circuit and activating the solenoid S to turn the motor in the direction to give left rudder and to bring the craft back on course. In this instance the solenoid S has no neutral positions but is at once activated to turn the motor to give right rudder as soon as left rudder ceases. As the wiring circuit for such solenoids are well understood, no special illustration is deemed needed. The craft will not continue on right rudder because as soon as the craft swings to starboard, the circuit through the cup 21 will again 'be closed. By appropriate setting of the abovedescribed compensating device it is possible to steer practically as close a course with alternate circuits as it is with alternate circuits and a neutral position between them. The out-of-circuit east-west cup which acts as a stabilizer prevents the yoke 20 from being tilted so far that its oscillations continue unduly long, a phenomenon every helmsman has witnessed when a free magnetic needle has been shaken by a wave.

It will be seen that the entire construction of both the preferred embodiment and the modifications thereof is very simple and inexpensive and may quickly be installed on any craft. No high voltage electronic tubes are required. The only exposed sparking element is the mercury 27 in the cups 21 and 22, and the spark from this is so slight, due to low voltage, and so guarded as to be unnoticeable. Full compensated steering is provided for, with limits which keep the craft on course.

I claim:

1. In an automatic pilot for a craft having a rudder and having means activated to indicate or to effect a correction to said rudder when the craft is ofi-course, apparatus for activating said corrective means comprising a bar magnet, an azimuth card rotatably mounted, a pair of mercury cups on the north-south axis of said card, a gimbal bar mounted in said cups having a counterweighted central portion below the level of said cups; a second pair of mercury cups in easterly-westerly alignment on said card; and a yoke for said bar magnet fastened to said central portion of said gimbal bar and extending upwardly therefrom and having end portions extending to said east-west mercury cups, said end portions alternately making contact with the mercury cups respective thereto when said yoke and said gimbal bar are tilted by said bar magnet, the east mercury cup and one of the north-south cups being terminals of one circuit, the west mercury cup and the other of said north-south cups being terminals of a second circuit, said circuits controlling said corrective means.

2. In an automatic pilot, apparatus for activating corrective means as set forth in claim 1, in which both of said east-west mercury cups are adjustable in height.

3. In an automatic pilot, apparatus for activating corrective means as set forth in claim 1, in which said yoke is of light wire resistant to immersion in mercury, and is carbonized at its end portions to prevent formation of mercury amalgam thereon.

4. In an automatic pilot for a craft having a rudder and having means activated to indicate or to etfect a correction to said rudder when the craft is off-course, apparatus for activating said corrective means comprising a bar magnet, an azimuth card rotatably mounted, a pair of cups on the north-south axis of said card, a gimbal bar having its ends supported in said cups and having a heavy central portion below the level of said cups whereby it is balanced in said cups, a pair of cups in easterly-westerly alignment on said card, one of said cups containing mercury, and a yoke secured to said central portion of said gimbal bar and extending upwardly therefrom so as to stanchion said bar magnet and having end portions extending to said east-west cups, that end extending to the mercury-containing cup making electrical contact therewith when said magnetic bar exerts a tilting force on said yoke in that direction, said mercury-containing cup and one of said north-south cups being bridgeable 'by said yoke and said gimbal bar to provide an electric circuit controlling said corrective means.

5. In an automatic pilot, apparatus for activating corrective means as set forth in claim 4, in which the other of said east-west cups is adjustable in height to provide a dampening to oscillations of said yoke.

References Cited in the file of this patent UNITED STATES PATENTS 507,522 Ayton Oct. 31, 1893 774,693 Peterson Nov. 8, 1904 1,015,061 Nelson Ian. 16, 1912 1,360,694 Sperry Nov. 30, 1920 1,378,740 Walkup May 17, 1921 2,059,271 Parker Nov. 3, 1936 2,068,065 Neubert Jan. 19, 1937 2,221,311 Hodgman Nov. 12, 1940 2,448,778 Crise Sept. 7, 1948 2,498,223 Rommel Feb. 21, 1950 

